The purpose of this project is to study the osmotic behavior of platelets and other blood components during the introduction and removal of cryoprotective agents (CPAs) from both an analytical and an experimental point of view. Comparison of the theoretical predictions of cell behavior during CPA introduction and removal based upon a non steady state mass transfer model with experimental observations of the responses of cells to changes in the composition of their suspending media will hopefully facilitate the development of optimum CPA introduction and removal protocols.